Evaporator for refrigeration machines



' June 18, 1935. A. TEVES 2,005,013

EVAPORATOR FOR REFRIGERATION MACHINES 7 Filed Jan. 29, 1932 A TTORNEYJ.

Patented" June 18, 1935 UNITED STATES PATENT OFFICE EVAPORATOR FORREFRIGERATION CHINES Alfred 'leves, Frankfort-on-the-Main, GermanyApplication January 29,

1932, Serial No. 589,737

The present invention relates to evaporators for refrigeration systems.Evaporators of the flooded type as most commonly used consist of areservoir or tank having connected thereto a plurality of tubes openingat both ends into the res- .ervoir member, with one or both ends of suchtubes below the normal level of the refrigerating liquid in thereservoir, which level is governed by a float and float-controlled inletvalve, the float being within the reservoir.

In such devices the tubes are ordinarily all fllled with the refrigerantliquid during idle periods,

and when the compressor is started and the pressure reduced in theevaporator, rapid boiling begins in the tubes, and the gas generated inthe tubes lifts the liquid in the tank, often completely filling it andinterfering with the action of the float and its valve by prematurelyand irregularly lifting the float and closing the valve. During suchperiods, regular vaporization is hindered and uniform flow isimpossible.

Among the objects of this invention, therefore, is the overcoming ofthis difficulty, and provisionof means for preventing such undesirableinterference with the operation of the float valve, thereby enabling thevalve to keep the level constant at all times and by preventing improperclosure of the valve, as well as by reason of the arrangement of thepipes, insuring uniform and more rapid flow.

Other objects will readily occur to those skilled in the art uponreference to the following description and the accompanying drawing, inwhich Figures 1 and 2 show respectively a side elevation and an endelevation, partly in section, of an evaporator incorporating theinvention;

Figure 3 is a side view similar to Figure 1 of a modified form;

Figures 4 and'5 are sectional views of further 40 modifications; and

Figure 6 is a plan view of the device of Figure 5.

As indicated in the drawing, the evaporator comprises a reservoirportion, designated III in the first illustrated embodiment, adapted tocontain a body of liquid refrigerant II, the level of which iscontrolled by a float II, which actuates a valve IS. The valve controlsthe'inflow of liquid refrigerant through pipe H to maintain the level22. Refrigerant vapors may be carried off through a pipe, as thatdesignated II, to the suction side of a suitable compressor, and then toa condenser (not shown) where it is again liquefied, all in theconventional or any desired manner, and returned to the evapofloat I!may be' an open pan into the body of which the suction outlet tube 5-opens in such manner that it prevents the collection of and removes anyliquid refrigerant in the float.

Referring specifically to Figures 1 and 2, it will be seen that theevaporating tubes are of two types, designated respectively 20 and 25.The.

- tubes-20 have both their inlet ends 20' and their outlet ends 20"arranged above the float-determined liquid level 22, with the inlet endsorlly slightly above the level 22. All of these evaporating tubes 20,which may be termed the working tubes", and which preferably exceed innumber the control tubes 25, as shown, may be in the form of dependingloops which extend well below the liquid level, although other suitableforms may be used and a greater or lesser'number employed, as may befound expedient.

In the second or control tube group the tubes are designated 25, and areso connected to the reservoir that their inlet ends 25' are below theliquid level and their outlet or discharge. ends 25" above it. Theoutlets of both tube systems, as 20f'-25", may be guarded by baffles 28adapted to prevent violent discharge of liquid and vapor against or uponthe float It.

In operation, when the system is at ,rest, the level stands idle andsubstantially undisturbed at 22 and no evaporation occurs, the tubes 26being of course filled to the. same level, and the tubes 20 ordinarilyempty. When the compressor isstarted and the system begins to work,boiling occurs in tubes '25, wherein of course the evaporation is earlyand relatively violent. The gas generated in those tubes forcesthe-liquid out of them and into the tank, where it raises and disturbsthe level 22, thereby permitting liquid to enter the tubes 20 throughinlets 20'. The tubes 20 of course stand empty while the system is idle,and my improved evaporator therefore uses less refrigerant than do moreconventional flooded evaporators. when the refrigerant overflows intothe tubes 20 in the described manner, it boils rapidly and is quicklyand completely gasifled. Since these tubes do not stand with liquid inthem while the system is idle, upon commencing to function they cause noviolent belching of mixed liquid and gas, and do not lift the entirebody of liquid refrigerant in the tank, in the manner above alluded to.Proper operation of the float is accordingly not interfered with,although a rapid circulation of the boiling refrigerant in the nature ofa whirling action takes place. The capacity of the tube system 2i'may beJust sufficient to raise 55 the level 22 a desired amount to cause theoverflow into the tubes 20, and this raising of the level is donerelatively smoothly by reason of the lesser influx from the tubes 25,while the jets from both the outlets 20"-25" are further prevented frominterfering with operation of the float by the baffles 26.

The construction shown in Figure 3 will be seen to be somewhat modifiedin that a closed float I20. is employed, and the suction or outlet tubel5a opens directly through the side wall and into the interior of theevaporator tank. The arrangement of parts will be seen to be otherwiseanalogous, and equivalent portions have accordingly been given likereference characters with the addition of the distinguishing charactera. thereafter, and need not be described in detail.-,

In the modified form of boiler shown. in Figures 5 and 6, the workingevaporating tubes 20c discharge at one end, as at 200', into the reservoir ilic above the normal liquid level 220, and at their other (inlet)ends are connected to the bottom of a header 300. The header 300 is alsopositioned somewhat above the liquid level 220. The inlet ends of thecontrol tubes 250 are connected to the reservoir I00 below the liquidlevel, as at the bottom thereof, and discharge as at 250" into the upperpart of header 300. Only the control tubes thus normally stand withliquid in them during idle periods, in analogous fashion, while theworking tubes 20c stand empty. Moreover,

by virtue of the isolated header 300, through which the output of mixedgas and liquid is delivered from the control tubes directly to theworking tubes, the precise increase of level caused by the discharge ofthe control tubes is not a matter of concern, as in the firstembodiment, and since the working tubes stand empty when idle and are ofgreater capacity than the controlgtubes, they completely vaporize thepartly liquid refrigerant delivered to them by the control tubes, andthus cannot belch liquid into the tank or lift the entire body of liquidin the tank to disturb the float operation.

While the interposed header may be outside the main evaporator tank, asin the embodiment just described, it may also be arranged inside butisolated from the same, as in the embodiment shown 'in Figure 4, inwhich the header is'designated 30b, and in which to otherequivalent'parts like reference numerals have been applied, with thesubstitution of the distinguishing characterflb;

a reservoir for liquid refrigerant, a plurality of refrigerating tubesconnected thereto each having a portion below but both ends arrangedabove the normal level of liquid refrigerant, whereby they are normallyempty of liquid refrigerant, and at least one refrigerating tubeconnected to said reservoir with its inlet end below the normal liquidlevel.

2. An evaporator as defined in claim 1, characterized by the fact thatthe capacity of the .the reservoir below the normal liquid level thereofis less than the total capacity of thefirst mentioned tubes.

' 4: An: evaporator for refrigerators comprising a'reservoirforliquidrefrigerant, a plurality of evaporatingtubes connected thereto,each having a' portion below but both ends arranged above the normalliquid level in the reservoir, one end of each tube being arranged toopen into the,

reservoir only a slight distance above such liquid level, and othertubes connected to said reservoirand having their inlet ends below saidlevel, whereby disturbances of the liquid level within the reservoirwill cause a certain amount thereof to enter the first-mentioned tubes.

5. An evaporator for refrigerators comprising a reservoir for liquidrefrigerant, an evaporating tube connected thereto below the normalliquid level to receive liquid refrigerant therefrom at all times, aheader arranged above the normal liquid level in the reservoir, to whichheader the outlet end of said tube is connected, and additionalevaporating tube means of greater total surface area and evaporativecapacity than said first mentioned evaporator tube, said additional tubemeans having the inlet end thereof connected to said header and theoutlet end to said reservoir above the normal liquid level therein.

6. An evaporator for refrigerators comprising a reservoir for liquidrefrigerant, an evaporating tube connected thereto below the normalliquid level to receive liquid refrigerant therefrom at all times, aheader arranged above the normal liquid level in and isolated from thereservoir, to which header'the outlet end of said tube is connected, andadditional evaporating tube means of greater total surface area andevaporative calevel therein.

' ALFRED TEVES.

